The Harmony runtime seeks to address software challenges of heterogeneous multicore architectures by the development of a software infrastructure that reduces the complexity of effectively and efficiently using these architectures and improves productivity with minimal performance loss. In particular we seek an infrastructure that i) implements execution models that bridge from existing languages and software development practices to commodity hardware systems and thereby leverage individual accelerator vendor compilation tool chains and programming models, ii) enables portable implementations across system configurations to amortize substantial software investments, and iii) delivers high performance by adapting applications to specific available accelerator capabilities across a range of system sizes and configurations. The initial target is multi-GPU systems to be followed by FPGAs and Cell processors.